lib/money/money/allocation.rb
# encoding: utf-8
class Money
class Allocation
# Splits a given amount in parts. The allocation is based on the parts' proportions
# or evenly if parts are numerically specified.
#
# The results should always add up to the original amount.
#
# The parts can be specified as:
# Numeric — performs the split between a given number of parties evenly
# Array<Numeric> — allocates the amounts proportionally to the given array
#
# @param amount [Numeric] The total amount to be allocated.
# @param parts [Numeric, Array<Numeric>] Number of parts to split into or an array (proportions for allocation)
# @param whole_amounts [Boolean] Specifies whether to allocate whole amounts only. Defaults to true.
#
# @return [Array<Numeric>] An array containing the allocated amounts.
# @raise [ArgumentError] If parts is empty or not provided.
def self.generate(amount, parts, whole_amounts = true)
parts = if parts.is_a?(Numeric)
Array.new(parts, 1)
elsif parts.all?(&:zero?)
Array.new(parts.count, 1)
else
parts.dup
end
raise ArgumentError, 'need at least one part' if parts.empty?
if [amount, *parts].any? { |i| i.is_a?(BigDecimal) || i.is_a?(Float) || i.is_a?(Rational) }
amount = convert_to_big_decimal(amount)
parts.map! { |p| convert_to_big_decimal(p) }
end
result = []
remaining_amount = amount
until parts.empty? do
parts_sum = parts.inject(0, :+)
part = parts.pop
current_split = 0
if parts_sum > 0
current_split = remaining_amount * part / parts_sum
current_split = current_split.truncate if whole_amounts
end
result.unshift current_split
remaining_amount -= current_split
end
result
end
# Converts a given number to BigDecimal.
# This method supports inputs of BigDecimal, Rational, and other numeric types by ensuring they are all returned
# as BigDecimal instances for consistent handling.
#
# @param number [Numeric, BigDecimal, Rational] The number to convert.
# @return [BigDecimal] The converted number as a BigDecimal.
def self.convert_to_big_decimal(number)
if number.is_a? BigDecimal
number
elsif number.is_a? Rational
BigDecimal(number.to_f.to_s)
else
BigDecimal(number.to_s)
end
end
end
end